The coagulometric methods involve a reagent of a known amount and specified temperature added to the specified amount of sample incubated for the specified time.
The clotting process is initiated by the addition of the reagent. Some optical characteristics of the sample is changing while a clot is being formed. The process of coagulation can be detected by several methods, of those, Yumizen instruments applies nephelometry, i.e. it monitors the change in scattered light intensity at 640 nm.
During coagulation, scattered light intensity increases and a sigmoid-like curve can be obtained. At the end of the assay, the clotting time can be obtained (in seconds) by establishing the coagulation point of the coagulation curve.